Brushless cooling fan

ABSTRACT

A fan assembly with an impeller and shroud for application in a vehicle cooling system. The fan is powered by an external rotor brushless direct current (BLDC) motor having an electronic controller positioned away from the BLDC on an outer shroud wall with a plurality of ducts drawing an airflow from a static lower pressure created by the impeller, the airflow streaming over a heat sink disposed on the controller, exiting through a shroud. The static lower pressure air is pulled by a centrifugal fan and skewed magnets inside the motor through a plurality of ducts in a shroud hub, cooling the BLDC, maintaining low resistance for high efficiency. The BLDC is integrated into the assembly, having a stator fixed in the shroud hub and a rotor directly fused to the impeller, the shroud and impeller forming the BLDC motor without a housing, allowing the motor to easily dissipate heat.

BACKGROUND OF THE INVENTION

The invention relates generally to a brushless cooling fan. Moreparticularly, the invention relates to a high efficiency brushless motorcooling fan for an automotive application.

Internal combustion engines, automotive engines as a prime example,require cooling. Typical cooling systems involve pumping a coolant overthe heat generating systems and pumping the heated fluid to a fan-cooledradiator to release the heat to the atmosphere. Typically, a coolingsystem uses a brushed direct current (DC) motor to power the system fan.However, brushed DC motors are inefficient and prone to mechanicalfailure. Brushless direct current (BLDC) motors overcome the lowerefficiency, susceptibility to mechanical wear and consequent need forservicing, the characteristic limitations of brushed DC motors.

In a BLDC motor, an electronic controller replaces the brush andcommutator assembly of the brushed DC motor, which continually switchesthe phase to the windings to keep the motor turning. BLDC motors havegreater reliability, reduced noise, longer lifetime, more power,eliminate ionizing sparks from the commutator, and reduceelectromagnetic interference (EMI), allowing for easier compliance withelectromagnetic compatibility (EMC) requirements. Since most modernvehicles incorporate computer controls in engine management and othergeneral vehicle operations, reducing EMI is important for thereliability of the overall vehicle.

Brushless motors are more desirable than a conventional brushed motor,but come at the cost of potentially less rugged and more complex andexpensive control electronics. These control electronics are not wellsuited for functioning under the hood of an automobile, where hightemperatures generated by the engine create a hostile environment forthe complex and expensive electronics. The operating life of theelectronics at high temperature is significantly reduced due to higherresistance levels. This limits the reliability of an electronic controlsystem, and consequently, the BLDC motor in high temperatureenvironments. The higher cost, increased complexity and limitedreliability at high temperatures have curtailed the adaptation of BLDCcomponents in under-the-hood automotive applications. Modern automobileswith more powerful engines paradoxically need both an efficient,powerful, and reliable cooling system and generate relatively hightemperatures hostile to BLDC electronic control systems. Under the hood,automotive components can reach temperatures greater than 100° C., theboiling point of water. The fan assembly is mounted in close proximityto the heat exchanger or radiator, where temperatures approach 110° C.To increase efficiency and operating life, sufficient cooling of the fanmotor and its electronic components is imperative.

Many have proposed various answers to improving the cooling system witha brushless motor. Kershaw et al. (U.S. Pat. No. 6,208,052) discloses aheat sink structure at the base of the motor with the shaft of the motorattaching to the heat sink. A control unit circuit board is between theheat sink and a hub in the shroud base. Kershaw et al. (U.S. Pat. No.5,944,497) previously had proposed an opening in hub where the motor iscooled by air directed by a plate from the high pressure region of thefan to the low pressure region of the fan.

Sunaga et al. (U.S. Pat. No. 6,661,134) proposes a heat sink withsupporting legs that are in contact with the electric circuit board sothat the heat sink is positioned on the electric circuit board. Theradiating fins of the heat sink are exposed to the outside through anopening in the circuit protection case adjacent to the motor. Takeuchiet al. (U.S. Pat. No. 5,947,189) suggests a radiation fin unit of thecontrol device inside the shroud that projects into an air guiding ducton the top of the controller. Nelson et al. (U.S. Pat. No. 6,600,249)proposes the controller of a brushless motor connecting to enginecontrol mechanism and mounted to the side of the fan shroud in housingwithout any cooling mechanism.

In addition to the heat generated by the internal combustion engine, aBLDC motor generates heat internally. Although brushless motorstypically operate cooler than conventional brushed motors due to theelimination of commutator-brush friction, common to both BLDC andconventional motors is the presence of copper magnet-wire coils found onthe stator or armature. When electrical current passes through thesecoils, the electrical resistance within the copper magnet-wire producesheat. High temperatures increase electrical resistance, requiring moreelectricity to generate the same magnetic field and producing even moreheat, creating the potential for thermal runaway, leading to burnout ofthe coils and destruction of the motor and other critical components.

Many have suggested ways to cool a fan motor itself. Hong et al. (U.S.Pat. No. 7,244,110) proposed a fan with a specially designed hub, theinside of the hub having vanes that become a radial-flow blower drawingcooling air through a brushed motor, not a BLDC motor. Yapp et al. (U.S.Pat. No. 5,489,186) proposes stationary flow control vanes that attachto the housing, moving and recirculating the airflow in a pathwaybetween the fan and the housing. Hayashibara (U.S. Pat. No. 4,428,719)discloses a rotor of a BLDC motor fixed to a centrifugal fan while astator is fixed to the scroll concentrically with the rotor, cooling themotor and eliminating the necessity for the motor housing. De Filippis(U.S. Pat. No. 5,217,353) suggests a BLDC motor having a casing withholes for taking in air from outside for ventilating the interior of thebrushless motor and a rotary part with holes which act as outlet ductsfor the internal ventilation air.

The marketplace demands that these axial fans that are used inautomotive cooling systems be both efficient and compact to fit in thelimited space under the hood. Many have proposed way to either increasethe air flow or condense the space required for the fan assembly.Alizadeh (U.S. Pat. No. 5,755,557) suggests a hub portion with a set ofblades extending to a circular support and a second set of bladesextending radially outwardly from the support. Similarly, Jorgensen(U.S. Pat. No. 4,962,734) discloses a fan ring around the fan blades andan assembly around the ring bearing the weight of the fan. Longhouse etal. (U.S. Pat. No. 4,685,513) incorporates an enveloping shroud which isfixed to the radiator and which has integral bracket structure forsupporting the fan motor centrally therein. Carlson et al. (U.S. PatentApplication Publication 2006/0257251) also has a hub with radiallyextending fan blades to an annular shroud, and a second set of fanblades extending from the shroud. Zeng (U.S. Pat. No. 5,591,008)discloses a motor fastened to a shroud, and a fan fastened to the motor.

Besides the necessity of cooling the motor and the controller forefficient operation of the fan, the blades of the fan impeller must bebalanced to reduce unwanted vibration in the rotating fan assembly. Theends of the impeller blades typically attach to a rotating rim whichmust be annularly balanced for smooth rotation without vibrating.Similarly, many have thought about balancing wheels or crankshafts onautomobiles where wobble is undesirable. Turoczi (U.S. Pat. No.3,663,328) discloses indicia cemented to a side wall of a tire forbalancing. Benjamen (U.S. Pat. No. 5,591,008) describes adding plugs toa wheel to balance a tire as well as pockets on a vibration damperaround the crankshaft. Warner (U.S. Pat. No. 2,454,852) discloses a fanon a rotary valve of the crankshaft having balancing holes drilled inrim. Darnell (U.S. Pat. No. 2,558,737) suggest balance weights addedonto the surface of the rim of the fan, which would create turbulent airflow. Wrobel (U.S. Pat. No. 5,591,008) discloses a fan impeller with oneor more guide rings provided with pockets or bores for weights.

A special challenge for an automobile owner who desires to switch to aBLDC fan as part of customizing the vehicle is finding a universal BLDCfan that will work in his or her vehicle. It is desirable to produce aBLDC that adapts to many different makes and models of cars by acceptinga range of voltage inputs to the controller and can adjust the fan speedbased on engine requirements. Mackelvie (U.S. Pat. No. 7,121,368)proposes to control the fan speed with some type of speed sensor and apotentiometer on the flap on an axle. Samuel et al. (U.S. Pat. No.4,124,001) discloses a temperature sensing system to vary fan speed witha potentiometer. Makarana (U.S. Pat. No. 7,088,062) suggests a methodusing a pair of fans, the second fan controlled by a variable frequencypulse width modulated (PWM) control signal to meet cooling requirementsof an engine. Wilke (U.S. Pat. No. 4,347,468) proposes an electronicvariable speed automotive blower control system controlled by apotentiometer on the dashboard. Lazebnik et al. (U.S. Patent ApplicationPublication 2010/0119389) suggests a modular brushless motor that may bereconfigured for different applications and power levels by varying thenumber blades on the fan and coils in the stator.

While these units may be suitable for the particular purpose employed,or for general use, they would not be as suitable for the purposes ofthe present invention as disclosed hereafter.

SUMMARY OF THE INVENTION

It is an object of the invention to produce a brushless motor coolingfan that has a rugged electronic controller resistant to a hightemperature under an automobile hood. Accordingly, the invention is abrushless motor cooling fan having an electronic controller protected bya heat sink that transfers heat away from the electronic controller.

It is another object of the invention to produce a brushless motorcooling fan that protects an electronic controller on a brushless motorfrom heat generated in the brushless motor during operation.Accordingly, the invention is a brushless motor cooling fan with anelectronic controller placed away from the brushless motor and the heatassociated with the operation of the brushless motor, the electroniccontroller disposed on an outer wall of a fan shroud.

It is yet another object of the invention to produce a brushless motorcooling fan that cools an electronic controller module on a brushlessmotor with a cooling airflow. Accordingly, the invention is a brushlessmotor cooling fan with a plurality of air ducts through an electroniccontroller module, the air ducts drawing a cooling airflow from a staticlower pressure of a rotating impeller, the airflow streaming throughducts over the heat sink, exiting through a duct in the fan shroud.

It is a further object of the invention to produce a brushless motorcooling fan with a high efficiency brushless direct current motor(BLDC). Accordingly, the invention is a brushless motor cooling fan witha plurality of air ducts through a BLDC, the air ducts drawing a coolingairflow from a static lower pressure of a rotating impeller through aplurality of ducts in a shroud hub, cooling the BLDC, keeping theresistance low for high efficiency.

It is yet a further object of the invention to produce a brushless motorcooling fan with a rugged brushless direct current (BLDC) motor that hasa rotor that is cooled by air. Accordingly, the invention is a brushlessmotor cooling fan with a BLDC motor with a centrifugal fan and aplurality of skewed magnets inside the motor, drawing cooling airthrough the BLDC and cooling the BLDC, improving the efficiency,durability and ruggedness by lowering the temperature of BLDC duringoperation.

It is a still further object of the invention to produce a brushlessmotor cooling fan with an integrated brushless direct current motor(BLDC) that dissipates heats to the surroundings. Accordingly, theinvention is a brushless motor cooling fan with an external rotor BLDCmotor having an outer rotor rotating around a stator, the stator fixedin a shroud hub, the rotor directly fused to an impeller fan without ahousing, the stator in the shroud hub and the external rotor with theimpeller fan integrating to form the BLDC motor and the rotordissipating heat directly to the surroundings.

The invention is a fan assembly with an impeller and shroud forapplication in a vehicle cooling system. The fan is powered by a highefficiency external rotor brushless direct current motor (BLDC) that hasa rugged electronic controller positioned in a module away from the BLDCon an outer wall of the shroud with a plurality of air ducts drawing acooling airflow from a static lower pressure created by the impeller,the airflow streaming over a heat sink disposed on the controller,exiting through a duct in the shroud. The static lower pressure air flowis pulled by a centrifugal fan and a plurality of skewed magnets insidethe motor through a plurality of ducts in a shroud hub, cooling theBLDC, keeping the resistance low for high efficiency and reliability.The BLDC is integrated into the assembly, having a stator fixed in theshroud hub and an external rotor directly fused to the impeller, theshroud and impeller forming the BLDC motor without a housing, allowingthe rotor and stator to easily dissipate heat directly to thesurroundings.

To the accomplishment of the above and related objects the invention maybe embodied in the form illustrated in the accompanying drawings.Attention is called to the fact, however, that the drawings areillustrative only. Variations are contemplated as being part of theinvention, limited only by the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like elements are depicted by like reference numerals.The drawings are briefly described as follows.

FIG. 1 is a diagrammatic perspective view of a brushless cooling fanfrom the rear.

FIG. 2 is a diagrammatic perspective view of the brushless cooling fanfrom the front.

FIG. 3 is an exploded view of the brushless cooling fan from the front.

FIG. 4 is a front elevational view of an electronic controller module(ECM) mounted on a fan shroud of the brushless cooling fan.

FIG. 5 is a cross-sectional view of the ECM mounted on the fan shroudfrom the front.

FIG. 6 is a diagrammatic perspective view of an impeller rim, the shroudwith the ECM mounted from below.

FIG. 7 is a diagrammatic perspective view of the ECM from the top of theshroud.

FIG. 8A is a diagrammatic perspective view of a brushless direct current(BLDC) motor from the rear.

FIG. 8B is a diagrammatic perspective view, similar to FIG. 8A, of theBLDC motor from the front.

FIG. 8C is a diagrammatic perspective view of a hub and a core on theshroud from the rear.

FIG. 8D is a diagrammatic perspective view of a rotor and a plurality ofskewed magnets inside the rotor.

FIG. 9 is a diagrammatic perspective view of an inside rim of theimpeller.

FIG. 10 is a cross-section elevational view of the ECM showing a coolingairflow pathway through the ECM.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 illustrates a brushless cooling fan assembly 20 for applicationin an cooling system of a vehicle with an internal combustion engine.The fan assembly 20 is powered by a high efficiency external rotorbrushless direct current (BLDC) motor 100. The form and construction ofthe fan assembly 20 allows for the efficient and reliable operation of avehicle cooling system that eliminates the drawbacks of BLDC motors,especially operating in a high temperature environment found under avehicle hood. This is accomplished by strategic positioning a pluralityof critical components and integrating these components with a pluralityof air ducts 42, 34 for forced air convection cooling as explainedhereinbelow.

The fan assembly has the open architecture (BLDC) motor 100 with anelectronic control module (ECM) 40, an axial fan impeller 50 and a fanshroud 30, each having an innovative structure that promotes cooling ofcritical electronic components. The cooling fan assembly 20 is uniquelyfashioned to protect critical components such as the ECM 40 from hightemperatures found under a hood of the vehicle. The axial fan impeller50, having a plurality of blades 52, is the primary fan used to cool thevehicle engine. The electronic control module (ECM) 40 controls the BLDCmotor 100, which in turn, rotates the axial fan impeller 50. The shroud30 mounts the fan assembly 20 with the BLDC motor 100, ECM 40 andimpeller 50 to the vehicle cooling system.

The shroud 30 having a central hub 32, is the assembly point for theimpeller 50, the control module 40 and the BLDC 100. The shroud 30 alsohelps with directing cooling air from the axial fan impeller 50 throughthe control module 40 and through the hub 32 to cool the BLDC 100. Theshroud 30 has a circumferential outer wall 36 with a base plate 38mounted on the outer wall 36, outside the shroud 30. The ECM 40 mountson the base plate 38 in a novel position, away from the BLDC motor 100,on the cooler outer wall 36 of the shroud 30 in a pathway of cooling airdescribed hereinbelow.

All BLDC motors require an electronic controller for operation tocontinually switch the phase of a plurality of winding inside the motorto keep the motor turning. The controller performs timed powerdistribution by using a solid-state circuit. The principals of how aBLDC motor is controlled by an electronic controller are well known tothose of ordinary skill and are beyond the scope of this discussion.Because the operating life of the electronics is significantly reduceddue to higher resistance levels at high temperature, cooling theelectronic controller is critical to the operation of the cooling fanassembly 20. The invention cools the electronic controller using threedifferent techniques, namely, by distancing the ECM 40 from the motor100, by providing a heat sink 44 and providing the duct 42 for a coolingair flow.

FIG. 7 shows the novel position of the ECM 40 on the outer wall 36 ofthe shroud 30. The shroud has an outer rear flanged edge 38. The ECM 40is placed on the edge 38 of the shroud 30 on the flat base plate 38. TheECM 40 includes a housing 46 containing the BLDC motor electroniccontroller, a fan switch connecting to a vehicle control system and atleast one connector, wired to the BLDC motor. The ECM 40 also includesthe heat sink 44 to dissipate heat by transferring the heat tosurrounding•air and a potentiometer 60. By separating the BLDC motor andthe electronic controller, the heat generated by the motor does nottransfer over to the controller, thereby reducing the operatingtemperature of the controller and extending its operation.

The heat sink 44 is mated to a plurality of high temperature integratedcircuits of the controller in the housing. FIG. 4 shows the heat sink 44having a plurality of fins 16 with a saw-tooth shaped top surface andsitting on the housing 46 containing the electronic circuits. The heatsink is held in place by a clip 48. The heat sink 44 is cooled byfocused convection cooling explained hereinbelow.

Cooling the ECM 40 is further accomplished by air convection coolingthrough a plurality of ducts. The focused convection cooling ducts(FCCD) further decreases operating temperature. As shown in FIG. 6, onthe edge of the outer wall 36 of the shroud 30 is the duct behind theECM base plate, formed by a sidewall 14 attached orthogonally to theedge 18 of the outer wall 36 of the shroud 30. The sidewall has a top14T and a bottom 14B, the bottom 14B attaching to the edge 18 of theshroud 30. The bottom 14B of the sidewall 14 has a duct opening 42Acreating an air exit adjacent to the sidewall. Referring to FIG. 5, thedrawing in cross section shows the clip 48 attaching to the top of thesidewall 14 and extending substantially above and over the fins 16 ofthe heat sink 44, the clip 48 have a plurality of fasteners 62 attachingto the housing 46. Between the top surface of the fins 16 of the heatsink 44 and the clip 48 are air ducts 64 created by a gap betweensaw-tooth surface of the fins 16 and the clip 46. Air flows past theheat sink 44 through the ducts 64 into the duct 42 adjacent to thesidewall 14 and out the air exit 42A in the shroud 30, the air enteringthe ducts 64 from the furthest away from the vehicle's heat source. As aresult, air that is focused past the heat sink fins 16 will be coolerand allow the controller to operate at lower temperatures. FIG. 10 showsthe path of the air flow starting above the fins 16 and flowing down theduct 42 at the sidewall 13 and out the exit 42A. Air flow through theducts 64, 42 is facilitated by the static pressure created by thecooling fan during operation. Theses three different techniques, namely,by distancing the ECM from the motor, by providing the heat sink andproviding the ducts for a cooling air flow effectively cools theelectronic controller for efficient and reliable operation. In addition,situating the ECM in this manner reduces obstructions that potentiallycreate turbulent flow and further reduces the air flow consumed incooling the ECM.

High temperatures effect the performance of the BLDC motor, the hightemperatures created both by the vehicle's engine as well as by the BDLCmotor itself. High temperatures negatively effect the efficiency anddurability of the motor. The invention cools the motor by having aplurality of air ducts for cooling airflow, by having a centrifugal fanand a plurality of skewed magnets inside the motor and having an openarchitecture external rotor directly attaching to the impeller, allowingheat to dissipate. As shown in FIG. 8C, the shroud has the center hubwith a hollow center core having a bore. In the center hub of the shroudis a plurality of cooling ducts. FIG. 8B shows a small centrifugal fan70 located between the motor 100 and the axial impeller blades 52, shownin FIG. 8A, dissipates heat from the BLDC motor 100 by focusedconvection air flow through the motor. The centrifugal fan 70 drawscooler air in from the front of the motor and exits through a pluralityof outlets 72 on the motor, shown in FIG. 8A. Air then passes throughthe BLDC motor effectively cooling the BLDC motor. The centrifugal fanand the plurality of skewed magnets rotates during operation drawing airthrough the cooling ducts 34 in the shroud hub 32 shown in FIG. 8C. Inaddition, lower static air pressure is created by the axial impellerblades during operation that promotes the flow of air through the BLDCmotor. The BLDC motor, having an open center, attaches to the hub 32having a core 74, the core fitting into the center of the motor. FIG. 8Dshows the skewed magnets 104 inside the flux ring 102 of the BLDC 100,the centrifugal fan 70 drawing air through the skewed magnets to coolthe motor.

FIG. 1 shows the brushless cooling fan assembly 20 from the rear. Theaxial impeller blades, each having a top 52T and a bottom 52B radiallyextend from the BLDC motor 100 to an annular rim 54, the bottom fixed tothe motor 100 the top fixed to the rim 54. The axial impeller blades 52use airfoil design that has a round leading edge 52R, a sharp trailingedge 52E, and in profile or cross section, look similar to a teardropthat has been flattened on one side. As air approaches the blade'sleading edge 52R, the stream splits and travels above and below theblade. Air is deflected across the convex curve along the top 52T of theblade 52 and along the flat or concave curve on the bottom 52B of theblade 52B, and flows downward over the sharp trailing edge 52E as itleaves the blade 52. The faster moving air across the top 52T of theblade creates less pressure than the slower moving air on the bottom ofthe blade. The twisted design of the blade ensures that the incidentangle between the airfoil and the airflow is constant along the bladelength, giving a uniform blade loading for high efficiency, low noisefans. At high static pressures, the blade twist is important, becausewithout it, the inner portion of the blade 52 will stall and permitreversed airflow, which, will seriously reduce the fan efficiency. Thehigh static pressure created by the airfoil design facilitate the airflow through the heat sink 44 of the ECM 40, cooling the ECM 40 which iscritical to the operating efficiency and reliability of the brushlesscooling fan assembly.

Referring to FIG. 9, when an odd number of blades 52 are provided in animpeller, it is necessary to balance the impeller. Placing weightsdirectly on the blade 54 has undesirable side effects, such as creatingturbulent air flow. In the present invention, a plurality of hollows 80are drilled into the edge of the fan rim 54 located about three degreesapart. These hollows can be selectively filled with a small amount oftungsten or another dense, high temperature melting substance,preferably in the form of a small ball 82, as needed in order toprecisely balance the fan, to create the high static pressure for airflow through the cooling ducts of the invention.

Referring again to FIG. 7, the ECM housing, having 46 a side 46S, hasthe potentiometer 60 attached to the side 46S of the housing 46. Thepotentiometer 60 is used in conjunction with a fan speed controller inthe vehicle control system. This allows the fan speed to be adjusted toprovide the desired cubic feet per minute airflow needed by the specifictype of car into which it is installed. The potentiometer 60 isselectively adjustable to a range of voltages from the vehicle controlsystem that are possible with various makes and models of automobilesthat would be customized with an aftermarket brushless cooling fan.

FIG. 3 shows the components of the brushless cooling fan assembly 20 inan exploded view. It is understood by those of ordinary skill that thisrepresentation shows different components separately for illustrativepurposes. The axial fan impeller 50 has the outer rim 54, a center ring56 and the axial impeller blades 52 radially disposed around the centerring connecting to the outer rim 54 in the airfoil design. In the outerrim 54 are the hollows for balancing the impeller 50 with weightedballs. The axial fan impeller 50 cools the vehicle engine, but the bladedesign and balance of the invention creates static pressure to directcooling air into the ducts of the invention to cool the BLDC motor 100and the electronic controller module 40. The center ring 56 is fused tothe BLDC motor 100 and is part of the motor as explained hereinbelow.

The motor 100 of the invention is preferably an external rotor BLDCmotor. The operation of an external rotor BLDC motor is well known tothose of ordinary skill, the details of which are beyond the scope ofthis discussion except to how the operation of BLDC motor relates tofeatures of the invention. In the external rotor BLDC motor the entireouter periphery of the motor rotates. The BLDC motor has a flux ring102, the plurality of skewed magnets 104, a stator 106, and a shaft 108.The outer periphery is the flux ring 102, a ferrous cylinder used tocontain the magnetic field of the skewed magnets 104 that rotates aroundthe stator 106. The flux ring 102 has an inner wall 102N, the skewedmagnets attaching to the inner wall. The stator 106 is stationary in theexternal rotor BLDC motor, the skewed magnets 104 and the flux ring 102rotating around the stator 106. The stator 106 has a center bore 110 andmounts in the hub 74 of the shroud 32, the core of the hub 74 insertingthrough the center bore 110 of the stator 106. Inside the core 74 of thehub 32 is the shaft 108 running through dual bearings in the center ofthe BLDC motor 100 used to align the external rotor 102 to the stator106.

The center ring 56 of the nonferrous axial fan impeller 50 adheres tothe flux ring 102 and moves as one piece, the axial impeller center ring56 and flux ring 100 are fused together using high temperature epoxyadhesive and positioning screws, assuring that the axial fan impeller 50is permanently and uniformly attached to the flux ring 102. The axialimpeller center ring 56 and the external brushless DC motor 100 areintegral components to the efficient operation of the axial fan impeller50. During operation, torque is evenly distributed to the impellerblades 52, creating the static pressure that creates air flow throughthe brushless cooling fan assembly 20. The centrifugal fan and theskewed magnets, which are not shown in this drawing, facilitate air flowthrough the motor 100 for cooling and sits inside the flux ring 102 andimpeller ring 56, drawing in the cooling air created by the staticpressure through the ducts.

The axial impeller center ring 56 bound to the flux ring 102 and stator106 mounted in the hub 32 of the shroud 30 eliminates the necessity fora separate “can” or motor housing, the impeller and the shroud of thefan assembly integrating together to contain the external BLDC motor100. In the external rotor BLDC motor 100, the internal components ofthe motor, the rotor including the flux ring 102 and the skewed magnets104 are exposed to the outside air. This design facilitate convectioncooling of the critical motor components. Cooling air enters the ducts34 on the shroud hub 32, which is further from the vehicle engine heatsource. Air flows through ducts 34, past the stator 106, between thestator 106 and the skewed magnets 104 and between each magnet 104,effectively cooling the stator 106 and the magnets 104. Air flow isboosted by the centrifugal fan and the skewed magnets in the motor andstatic pressure created by the axial fan impeller 50.

The shroud 30 has a front 30F, the front 30F has a plurality of supportarms 76 radially extending out from the hub 32 and connecting to theouter wall 36 of the shroud 30. At least one connecting wire is inside asupport arm 76, connecting the BLCD 100 motor to the electroniccontroller module 40. The base plate 38 for the ECM 40 mounts on theouter wall 36 of the shroud 30, with the attached sidewall 14 having theair duct 42 orthogonal to the base plate 38 and extending outwardly fromthe base plate 38. The ECM 40 with the heat sink 44 and potentiometer 60mount on the base plate 38 and are held in place by the clip 48. Airflow created by the static pressure of the impeller 50 moves across theheat sink 44 and exits out the duct 42 as described hereinabove.

The components described hereinabove of the brushless cooling fanassembly 20 are integrated to maximize the cooling of the BLDC motor 100and the electronic controller module 40. The airfoil design impellerblades 52, perfectly balanced by weights in the rim 56, create staticpressure causing cool air to flow through the BLDC motor 100 andelectronic controller module 40. The electronic controller module 40 ispositioned at a maximum distance from heat of the BLDC motor 100. TheBLDC motor 100 mounts in the shroud hub 32 that is integrated with theimpeller 50 to allow the rotor which includes the flux ring 102,impeller center ring 56 and the skewed magnets 104, of the motor 100 tobe exposed to the outside for additional cooling. The shroud hub 32 hascooling ducts 34 to assist the centrifugal fan and the skewed magnetsinside flux ring 100 to pull cooling air in further cooling the motor100, the cooling air flowing from the static pressure generated by theimpeller 50 optimally designed and balanced as described hereinabove.

In conclusion, herein is presented a high efficiency brushless coolingfan for retrofitting on a high performance automotive engine. Theinvention is illustrated by example in the drawing figures, andthroughout the written description. It should be understood thatnumerous variations are possible, while adhering to the inventiveconcept. Such variations are contemplated as being a part of the presentinvention.

1. A brushless cooling fan assembly for application in a vehicle coolingsystem, the assembly comprising: an axial fan impeller having a centerring, an outer rim and a plurality of blades fully extending radiallyfrom the center ring to the outer rim; a shroud for mounting the fanassembly in the vehicle cooling system, the shroud having a center hubwith a hollow core and an outer wall with a base plate mounted outsidethe outer wall, the shroud having an air duct exiting to the blades; abrushless direct current (BLDC) motor with a center bore and a peripheryfused to the center ring of the impeller, the hollow core of the shroudinserted through the center bore of the motor to operably couple themotor, the shroud and the impeller as one functional unit, the BLDCmotor powering the impeller and thereby creating heat, the impellerrotating with respect to the shroud and the motor and thereby creatingstatic pressure; and an electronic controller module having a housing,the housing having an electronic controller electrically connected tothe BLDC motor, the controller controlling the BLDC motor, thecontroller generating heat during operation, the electronic controllermodule mounted on the base plate on the outer wall to separate thecontroller from the BLDC motor in order to protect the electroniccontroller from heat created by the BLDC motor, the unit including thecontroller, wherein the module having a heat sink disposed on thehousing, the sink mated to the controller to dissipate heat away fromthe controller, the sink in fluid communication with the duct, whereinthe pressure facilitates air flow from the sink through the duct to theblades and thereby cooling the module.
 2. The brushless cooling fanassembly as described in claim 1, wherein the heat sink has a pluralityof fins, the plurality of fins having a sawtooth surface.
 3. Thebrushless cooling fan assembly as described in claim 2, wherein theelectronic controller module has a clip extending substantially aboveand over the fins of the heat sink, holding the heat sink on the housingand forming a plurality of ducts with the sawtooth surface of the fins.4. The brushless cooling fan assembly as described in claim 1, whereinthe sink has a plurality of fins, the flow occurs past the fins, theshroud having a plurality of hollows configured to be selectively filledwith a plurality of fillings in order to balance the impeller.
 5. Thebrushless cooling fan assembly as described in claim 1, wherein the BLDCmotor having internal operational components, the hub having a coolingpassageway configured for air flow, the passageway in fluidcommunication with the components and ambient air, wherein duringrotation of the impeller, the passageway facilitates air flow to thecomponents in order to convection cool the components.
 6. The brushlesscooling fan assembly as described in claim 1, wherein the BLDC motor isan external rotor BLDC motor, at least one of the blades has an airfoildesign.
 7. The brushless cooling fan assembly as described in claim 1,further comprising a fan located between the BLDC motor and the blades,the motor having an air outlet in fluid communication with ambient air,the fan draws cooler air from front of the BLDC motor and dissipatesheat from the BLDC motor by focused convection of the cooler air throughthe BLDC motor out through the outlet.
 8. The brushless cooling fanassembly as described in claim 1, wherein the module including apotentiometer configured for operable coupling with a fan speedcontroller in a vehicle control system.
 9. A brushless cooling fanassembly for aftermarket customization of a vehicle cooling system, theassembly comprising: an axial fan impeller having a center ring, anouter rim and a plurality of blades fully extending radially from thecenter ring to the outer rim; a shroud for mounting the fan assembly inthe vehicle cooling system, the shroud having a center hub with a hollowcore and an outer wall with a base plate mounted outside the outer wall,the shroud having an air duct exiting to the blades; a brushless directcurrent (BLDC) motor with a center bore and a periphery fused to thecenter ring of the impeller, the hollow core of the shroud insertedthrough the center bore of the motor to operably couple the motor, theshroud and the impeller as one functional unit, the BLDC motor rotatingthe impeller and thereby creating heat, the impeller rotating withrespect to the shroud and the motor and thereby creating staticpressure; and an electronic controller module having a housing, thehousing having an electronic controller electrically connected to theBLDC motor to control the BLDC motor, the controller generating heatduring operation, the module having a heat sink disposed on the housing,the heat sink having a plurality of fins, the heat sink mated to theelectronic controller to dissipate the heat away from the electroniccontroller, the electronic controller module mounted on the base plateon the outer wall to separate the controller from the BLDC motor inorder to protect the electronic controller from heat created by the BLDCmotor, the unit including the controller, the sink in fluidcommunication with the duct, wherein the pressure facilitates air flowfrom the sink through the duct to the blades and thereby cooling themodule.
 10. The brushless cooling fan assembly as described in claim 9,wherein the electronic controller module has a clip extendingsubstantially above and over the fins of the heat sink, holding the heatsink on the housing and forming a plurality of ducts with the sawtoothsurface of the fins.